Through the Fire
by VivaBean
Summary: It was a simple mission. One they could easily execute. Or so they thought. Getting caught in the grip of Gehenna, Rin disappears, leaving his brother and friends behind. Meanwhile, something else is stirring in Assiah! What will become of Rin? Rated M for violence and explicit scenes.
1. Chapter 1

**A/N: First and foremost, I do not own Ao No Exorcist or any of the characters. Pff, like I'm brilliant enough to create such gold. Second of all, this is my first full fledged fanfic. I do want to take the time to introduce myself and say hello! This fic follows the characters more from the manga, so there could be slight spoilers on their development. I have been planning this fic for a while now and I just want to let you know how much it would mean to me if you could take a few minutes out of your day to review! If not, it's no biggie. Not like I can find you and tie you to a chair and force you, right? Anywhosers, I am very excited to get this show on the road. I intend for this to be pretty long, so hopefully you'll be in it for the long haul! Welcome….to HELL. Just kidding. Well maybe. Who knows.**

* * *

 _ **I.**_

With a loud _THUD,_ Yukio Okumura dropped a manilla folder onto the desk in front of his older twin brother. Rin Okumura stared with wide blue eyes as he took in the sheer size. It had to have been at least 600 pages of paperwork within. His eyes shifted between the folder and his brother, disdain clearly pulling at his lips. Yukio responded with a raise of his eyebrow as he gestured for Rin to open it and read the content inside. Mumbling to himself, he flipped the first page open glanced at the top. _'_ _Haniko Murashima- 87-reports Jikininki sighting'._ Rin returned his gaze to his brother. "All this in one file for a Jikininki? Tch, you really work too much."

"It's really not that much compared to other reports. That's besides the point," the younger twin flipped a few pages and stopped on a map. "This older gentleman lives in a secluded area around Kiso. He just so happens to run a decently small cemetery, and as of late has been having issues with a Jikininki," he paused to make sure Rin was following. Seeing the clueless look on his face, Yukio continued. "A jikininki is a ghoul-typed demon. It preys on dead bodies, but can become greedy enough to start to prey on the living. It builds its home in cemeteries. They are better known as graveyard ghouls."

"Graveyard ghouls are weak against silver and heavy firearms. Their fatal verse is also known to be apart of John," Ryuji "Bon" Suguro cut in. Rin turned his gaze to his other classmates sitting amongst the cram room. Shima and Konekomaru nodded in agreement with him. Izumo sat a little farther away looking almost uninterested. Shiemi, on the other hand, was nose deep in the pages of the manilla folder. "This should be a piece of cake. We have dealt with bigger problems and have even taken on more powerful ghouls than something like this. I'm getting a little irritated by the level of these missions recently," Suguro crossed his arms and leaned back in his chair a little.

"I understand that. You of all people know we have to do what is given to us. Not every job is as enjoyable as others," Yukio paused as Rin scoffed. He cleared his throat and began again. "You're right. This should be simple. We go in, we get out," He paused to look at his twin. "That means following instructions. There shouldn't be _any_ issues. If I have to fill out _one more_ report on why things went haywire, I will make sure we won't be picking up missions until further notice. Do you understand?"

Rin stood up immediately, knocking his chair over behind him. "Why do you only look at me when you say that?" Which in turn prompted a look from Yukio that read ' _Do I really need to explain myself?'._ Rin shrank his shoulders and turned to pick his chair back up, sitting in it with a heavy sigh. "Fine. So when are we leaving?"

"Four a.m. on the dot. That will leave us plenty of time to set things up once we get there. We will meet at the front and take a bus up there. It's a decently long trip so bring something to keep yourselves' out of trouble," Yukio yet again shot a glance at Rin. "Shiemi, I assume you will be packing snacks?" Shiemi gave a quick nod as her face gleamed. "Let's try to make it edible this time," he tried to joke, the gleam immediately disappearing off of her face. "It looks as if we are out of time for today. Get your things packed and make sure you eat a decent breakfast. Don't be late."

* * *

The next morning Rin stood at the front of True Cross Academy alongside his brother. Fog still settled over the street and you could barely see forty feet in either direction. The silence was a little unsettling, Rin rocked back and forth on his heels while he rubbed his hands together and breathed into them. It was unusually cold considering it was summer. Yukio glanced at his watch and mumbled impatiently to himself. The others slowly appeared one by one, all with the same expression of death on their faces. The last one to stroll in was Shiemi, who seemed to be more than excited to go.

"I packed us all Sukiyaki!" Shiemi proudly raised the bags in her hands, receiving small grunts of appreciation from the other Exwires. Loud screeching of breaks emerged from the silence as a bus finally appeared from the fog. It seemed like an old school bus more over a city bus. Paint chips were falling off of it and it smelled of very pungent exhaust.. It came to a sudden halt in front of the group and with a loud creaking, the doors opened. They filed in, taking their seats and giving each other space. Each one wanting to have room to sprawl out their legs and take a nap for the rest of the morning.

"Good morning everyone!" Yukio raised his voice slightly to help get the young Exwire's attention, Grunts were all he received. "I hope everyone had a decent breakfast. I also hope you took it upon yourselves to do a little studying," His gaze shifted to Ryuji, Konekomaru, and Shima. "I'll be looking for you guys to be able to recite it's fatal verse. I have armed myself with bullets with silver deposits and if things go bad, I will be there to take over. I have the utmost faith in you guys though. Rin!" He yelled at his brother as he seemed to have dozed off. Rin quickly jumped up trying to act as if he was awake the whole time, wiping drool from his mouth with his sleeve. "I need you to keep a level head here. It's a simple job and I don't need you screwing things up. You are to only use your flames if we absolutely need them. Not like telling you this will do any good since you never listen anyways.."

"Hey, I do listen!" Rin interjected. "You just never let me do anything."

"Kiso has a small population, We don't need to be worrying them with your blue flames. Then you surely would be hearing it from the higher ups. Would you, just for once, humor me and not cause any trouble?"

"Can't promise anything," Rin crossed his arms and leaned his head against the window, trying to make out the scenery through the fog and the dark. _'How strange,'_ he thought. _'There's never usually this much fog this time of year… Maybe it will clear up once the sun shows itself'._

* * *

The bus shuddered and screeched as it slowed to a stop. Rin slowly opened his eyes, taking a moment for his eyes to adjust. _'Oh yeah. Kiso. Are we already here?'._ He stood and raised his arms above his head, stretching out his back. The others seemed to be waking from much needed naps as well. Placing his forehead against the window, Rin tried to make what was outside but could barely see through the fog. "What time is it? And what is with this weird weather?"

Yukio glanced at his watch and then back out the window. "It's two. We are definitely here….but something feels very strange." The bus doors creaked open and they slowly filed out. The fog was thick and the visibility was down to maybe ten feet at most. Floating amongst the fog were mass amounts of coal tar. Rin was the last to step down from the bus and buttoned up his uniform coat, letting out a quick sigh which you could see in the frigid air.

They stood in the middle of a cobbled road which looked like it needed a lot of maintenance. With the low visibility, there wasn't much to see other than where the road led and a big welcoming gate to the town. It was eerily quiet for the main part of Kiso. Yukio pulled out a flashlight to try and help navigate and led the group forward. As they made their way through the center, more buildings were coming into view. It almost seemed as if nobody was living here anymore. The doors were shut and the shops weren't open for the day. A lot of them looked worn down and seemed as if they hadn't been well maintained in quite a while. "What the hell…," Yukio muttered. He continued to lead them up a path towards the location of the old man's secluded cemetery.

"Is it just me or does the air seem to be getting heavier the closer we get? Not to mention these coal tars are getting ridiculous," Rin swatted a few from his face.

"Ugh quit your complaining. That's all you do," Izumo's eye was visibly twitching.

"For once I agree with her. It's not helping anyone's morale Rin. Just shush for once, wouldya?" Bon chimed in as well.

"All of you need to shut it. We are here," Yukio ended it as fast as it had started. The group came upon a run down hut and in the back you could barely make out what seemed to be headstones. "Keep your guard up," he stated as he wrapped the door three times with a fist. The door slowly opened, inviting them entry even though they didn't quite see who had opened it. The twins made it through the doorway with the others behind. "Mr. Murashima?" The younger one called out. "My name is Yukio Okumura. I am a middle-class exorcist here with a few exwires to help with the Jikininki?" There was only silence in return until Rin had spotted slight shuffling in the other room. He quickly walked over with his brother in suite.

Sure enough, standing in the next room was a hunched over figure around 5'9''. It was hard to see in the light, but the silhouette seemed that of a man of poor stature who was having trouble maneuvering around his own home. Yukio guided his flashlight in that general direction, giving more visibility to the man. His movements were odd to say the least. It was almost as if the man was using no muscles at all. His body remained stiff as he shuffled around. "Mr. Murashima?" Yukio repeated with a slight shake in his voice. The figure's head slowly started to turn as the rest of his body remained in place.

"I'm pretty sure normal humans can't do that…" Rin stated as the head finally stopped and was completely backwards on the man's body. Yukio's light rested on the contorted face. His eyes were non-existent and blood was pouring from the sockets, His ears were elongated and fangs hung from a crooked smile.

"Hello sons," a wicked voice arose from the man's throat. It almost sounded as if a hundred demonic beings were speaking in unison. Yukio immediately pulled out his cell phone and began dialing numbers frantically while telling the others to get the hell out. Blue flames spontaneously burst in the doorway, keeping the young exorcists from leaving. A laugh boomed from deep within the man, sending chills up Rin's spine. He quickly reached for Kurikara and unsheathed it, drawing his own blue flames.

"I've come to take you home. You don't have Shiro protecting you anymore. Stop avoiding what you truly are."

Bon quickly drew his bazooka from his back and shot it towards Mr. Murashima's possessed body. This bazooka was always the first resort in battle, hoping to stop it by exorcising demons before the battle gets too severe, With another laugh and a simple flick of his wrist, Satan sent Bon flying. He landed with a loud _CRACK_ as blood spurted out of his mouth. His hand came up to the center of his chest and he wrapped it around a sharp piece of wood that had impaled him. He let out a cry of pain and his eyes widened as he tried to pry the wood from his own body.

"Don't even try to move it! You'll cause more damage! Shiemi, do what you can for Bon!" Yukio nodded his head in Bon's direction and swiftly put his phone back. Pulling out his pistols, he took aim and shot with no hesitation. Two bullets landed in the enemy's face, dead center right between the eyes. With his crooked smile widening, Satan turned immediately in Yukio's direction, his eyes alit with blue flame.

"You. You are a disgrace to my name. Come here so Daddy can reprimand you!."

"Yamantaka, now would be a good time for your help," Shima called out as his flaming, four-armed ox-beast familiar appeared behind him. Yamantaka shoved Yukio out of the way just as Satan began to lunge for him. The familiar, eager to be fighting, let out a blast of black flames that was quickly extinguished by blue.

"Nii-chan we need Mr. Sancho!" Shiemi summoned Nii-chan with her summoning papers and had made her way over to the impaled Ryuji. "Just hang in there Bon," She stated through trembling lips as she tried her best to gather her composure. With gentle hands she applied the aloe plant to some of his wounds, but he was losing blood in surplus amounts.

"You think you guys can actually stand up to me? Me? A God. You are puny. You are nothing," Satan spat as a forked tongue protruded from his mouth. Licking his lips he raised his hand, bringing blue flames upon Yamantaka's entire body, disintegrating the beast entirely. "I'm offended that you fight with such weak attacks. Are you underestimating me?" The possessed man's body was now completely immersed in blue flames. Skin was starting to fall off as blood started pouring from his ears and nose.

"Eat shit!" Rin yelled from behind his father, coming down with incredible speed, sword clad in blue flame. As if timed stop, Satan turned and grabbed Kurikara by the blade and threw it from Rin's hands. In the blink of an eye, Satan had a hand wrapped around Rin's neck, keeping him suspended from the ground. "Tsk tsk. Such a pity. I was sure my spawn would have been more impressive than this. We will have to rectify that," He licked his lips, malicious intent easily visible. Satan raised his other hand and in one movement that was almost untraceable, shoved it into Rin's chest. Blood poured from Rin's mouth as he gurgled in pain. He frantically tried pulling at his father's arm until he could no longer keep his eyes open and his body went limp,

"Rin!" Yukio screamed out and he unloaded the rest of his clips into Satan. Again, a laugh of what sounded like thousands of demons in unison bounded from his chest. He raised his hand and Yukio fell to his knees. It almost felt as if there was a heavy weight bearing down on top of his shoulders. _'What is this feeling? I can't move!'._ Sweat dripped down into his eyes as his mouth hung open. Yukio could not get a single word out as he watched Satan take a few steps back towards the darkness. Something was moving on the ground. Focusing in, it seemed to be rotting hands reaching up from the ground. No, not just hands. Limbs. Full dismembered bodies. There was a chanting in his ears that was suddenly getting louder as the heap of limbs also grew. Yukio didn't know if the other's could hear it or not. With a sizeable shaking of the ground, what seemed to be a gate appeared out of the crawling amalgamation. Yukio's insides screamed as all he could do was sit there and watch as Satan disappeared into the gates of Gehenna holding his older twin brother. It took what felt like eternity for the gate to finally disappear and the weight felt like it had lifted off of him.

"Rin! Rin!" Yukio continuously cried out until you could no longer make out his brother's name through his tears. At that moment in time, several exorcists came in through the front to see the mess that lay before them. Bon was incapacitated from the amount of blood loss. Several medics came in to evaluate the group and extract them from the house. Others were already evaluating the scene. Bon was immediately taken to be treated while everyone else gave their statements as best they could. Everything was moving in slow motion. _'I let this happen. How did this happen?'_

* * *

It had been a week since the incident in Kiso. Yukio slowly ran his fingers over his brother's desk in their dormitory. Rin's possessions laid there as they were, untouched. With a heavy sigh, he sat on his twin's bed, clutching the sheets between his fingers. _'I wish I hadn't been so hard on him. I wish I…'._ There was a sudden knock on the door. Yukio quickly stood and rushed to open it, hoping someone might have had news on his brother.

"I know now is not the time, but I have some news," A calm voice stated through the doorway. Yukio's eyes widened as he met the gaze of a tall man in white and purple. "I know right now you probably want to find your brother, but we've come across something that needs your attention," he stepped past Yukio and entered the room. Yukio clenched his fists, trying to not let his disappointment show. _'I don't have time for this..'._ "I think this might interest you. It's really quite funny consi-"

Yukio raised a hand to cut of his speech. "It better be goddamn important Mephisto."

"We've come across a young girl. A nephilim. I need you on this one."

 **A/N: Oh goodness. I don't even know where to begin. Or even what to say. Meh! Just stick around for next week!**


	2. Chapter 2

**A/N: Sorry for the wait on the update. I'm in the middle of moving. Boo, adulting. I just got my internet turned on today so be expecting more updates soon! I had fun writing this one so enjoy!**

 _II._

Rin's eyes slowly flickered open. _'Why do I feel like shit?'_ The surrounding area was very dim, the only light he could make out was coming from under what he was assuming was a door. _'Where the hell am I?'_ Rin tried pulling his right hand to his face to rub his eyes, only to feel a sharp pain in his wrist. _'I can't move my arm'_ His left also had the same result. _'What happened..?'_ The memory of an old man with a backwards head and blue flames flashed into his head. _'Satan..'_ He yelled out in frustration as he tried moving his arms again. Getting fed up with the futility of it all, he focused his energy and created a flame to illuminate around him. He quickly located the source. In the center of both wrists were nails, at least six inches long, bored straight into wood. No. This was a cross. _'The hell?'_ Coming to the realization of being suspended, his eyes widened in fear. "Let me down! Hello?!" He trashed, but only for a moment. The door slowly opened as he heard a low whistling. The tune seemed oddly effervescent and yet it somehow filled Rin with dread. Along with the whistling, it seemed as if something was dragging. Metal against the floor.

"Question," A gravelled voice spoke so low, Rin had to completely focus to hear it. "What is the opposite of faith?" This time the voice seemed to have been coming from a completely different side of the room. "Not disbelief. Too final," it was now somewhere else. He couldn't keep up with what directions. "Too certain." Rin let out a cry of pain as a blunt force hit the left side of his face. "Too closed." He could feel warm liquid running down his neck. "Itself is a kind of belief," It was now right in front of him. "Doubt." There was another heavy blow right to the front of Rin's head. He could feel his flesh being torn away with the hit. He let out another painful cry as his body became immersed in his flames. Rin lifted his gaze to look the person in question, blood dripping into his vision. The mystery person was now completely illuminated by the light, yet the surrounding area was still pitch black. Shiemi stood directly in front of him, his blood covering her face and blouse. An amused smile tugged at the corner of her lips as she cocked her head. In her hand was an aluminum bat with what seemed to be jagged metal pieces welded to it. She had the end of it resting on the ground. "Oh my," the voice now imitating Shiemi's perfectly. She raised the bat and traced it up Rin's body, resting it under his chin. "How strong," the imitator licked her lips and moved the bat away from his face. "This should be fun."

"Who the hell are you?!" Rin screamed as his flames grew even bigger. He pulled his arms as much as he could, the nails slightly ripping through his wrists. "You think this is funny?" Blood continued to pour into his visage as his pupils contracted, his ears stretching to their demonic form. The Shiemi imitator cocked her head to the other side and giggled. She then dropped to the floor on her hands and knees. Her body started contorting and snapping as if it was reconstructing itself. Her skin started falling off in mass amounts like it had turned into liquid, pooling on the floor in front of her. The compilation of blood and skin started coagulating and reforming, reattaching itself to the contorted body. The figure stood up slowly and stretched out, letting the rest of the newly formed skin fuse to it's face.

"Is this more to your liking?" Before Rin stood an exact copy of the man who had raised him, Shiro Fujimoto. The demon raised his arms and smirked, revealing his fangs. "Would this make it easier for you? I'm not entirely sure how emotions work, but I know this old bag of bones meant _something_ to you, am I right?" The demon walked over in a languid manner, grabbing Rin by the chin and forcing their eyes to meet. "I want to know what you're feeling right at this moment. I want to know every fear, every thought of doubt that might be running through that adorable little head of yours." His hand moved up to Rin's hair and ruffled it. "Tell me, are you afraid of what you are?" The demon grabbed the back of his head forcefully and lifted it up, bringing Rin nose to nose with him.

"I'm going to kill you," Rin spat in the demon's face. "I don't care who you become. Just wait until I get down from here!"

The demon's mouth twitched and he suddenly burst out with laughter. Taking a moment to gather his composure, he stepped back a bit from the suspended Rin. "Ha..you are amusing. Fortunately, that's what I am here for," he closed the space between them again. "And from the belly of the beast, it descends," the demon lifted his head towards the ceiling and reached an arm deep into the back of his throat, his jaws adjusting accordingly. He slowly pulled out what Rin immediately identified as the Kurikara sword. The demon smiled at Rin's expression and he slowly unsheathed it, delighted as more of his flames were unleashed. "Let's begin by breaking this awful attitude of yours, shall we?" and with that he brought the sword down upon his knee and shattered it in half.

With huge blue flames consuming the room, Rin ripped himself from the wooden cross, his powers being completely released from the sword. His ears were at full length and his pupils now slit. He bared his fangs as his face took on a complete animalistic look. Locking onto the shapeshifting demon, Rin launched himself and reached out to grab it by the face. Their bodies collided, sending them toppling to the ground. Rin pinned the false Shiro to the ground by his arms, dark black nails digging into its skin. The demon's face was nothing but excited as he watched Satan's son unleash his anger. With a demonic scream, Rin continuously laid punch after punch onto the demon's face, slowly denting it in. The demon never let the smile leave his face. Finally pulling away and breathing heavily, Rin stepped off taking a look at what he had done. There was nothing left of the face of the man who raised him. _'Why does this feel so gratifying?'_ A single tear ran down his face as he dropped to his knees. His hands shook as he raised them and studied his blood covered knuckles. A slow clapping sounded from behind him.

"It feels great, doesn't it?"

' _That voice..'_ Rin quickly stood and turned his body to face the location of the clapping. "Show yourself!" he let out with a roar, followed by a flame that burst into the darkness. _'Nothing's there?'_

"I see you had no issues putting a damper in Carreau's fun. As is expected of my bloodline," Satan placed his hand on his son's shoulder, causing Rin to stiffen and clench his fists. He let out a boisterous laugh. "It'll take him a little to recover from that. You left him with no head!" The laugh seemed to emanate from the entire room. Rin's eye visibly twitched in anger and he quickly turned to face his father, only to yet again find nothing there. "Stop being such a coward and come face me," Rin shouted, spreading his arms out wide. "Or are you too afraid that your son will put you out of power?!"

"SILENCE!" The room shook. A moment of silence passed before the voice spoke again. "You are an incredible being, son. The fact that you can exist in Assiah is beyond comprehension." There was a snapping of fingers and Rin suddenly found himself in another room, bound to a table with his limbs sprawled out. Instead of nails holding him down, there were some serious steel chains attached to his wrists and ankles. "You are the greatest weapon. _My_ greatest weapon. My powers existing in Assiah? It's glorious. You will be the one to join both Gehenna and Assiah. Son, together we could rule both realms!"

"Shove it, you ugly beast," Rin retorted with a sneer. "I don't think that sounds fun at all. What I really want is to kick your ass!"

Satan let out another laugh. "Yeah, we will see about that. We will break you soon enough."

* * *

Yukio quickly made his way to the Vatican headquarters, rain drenching his exorcist's coat. He held his arm above his head, trying to keep the water from hitting him, but it wasn't much help. He reached the golden doors of the massive building and quickly stepped in the Japan branch to avoid the rain. With a heavy sigh, he hurried up the stairs into the main court room. As the wide french doors swung open, Yukio took in the scene before him. There stood Mephisto Pheles in all his white and purple glory with what seemed to be a young girl, maybe the age of five. Mephisto eyed Yukio as he walked up, then turned his attention back to the heads of the Vatican.

"You seem to have just as much issue letting an angelic being live as you did with the spawns of Satan," Mephisto said calmly, a grin plastered on his face. "She is a child of God. Besides, you should see what she can do to demons!" He clapped his hands together in excitement and awaited the reply from the Cardinal. There were whispers among the others and it took what seemed forever before one finally spoke.

"Let's see it then," the Cardinal raised his hand gesturing Mephisto to hurry and show what the child could do. Mephisto's grin became sickeningly wide and he spun on his heels to face the child. She was a cute little thing, with dark brown curls that rested on her shoulders. Her big grey eyes looked clueless as they bounced between Mephisto and the Vatican members.

"Eins, swei, drei," True Cross's director meticulously pointed his umbrella in front of the girl, and before their eyes a tiny hobgoblin appeared. Immediately, the monkey-like demon started running sporadically towards the exit, only to be stopped by Yukio's foot. The tiny demon looked up and their eyes locked. "Yukio, if you would please bring him here," Mephisto gestured for him to hurry. Yukio grabbed the hobgoblin by the tail as it tried to swing its arms at him. "Little girl, look at this cute little thing. Would you like to pet it?" The girl nodded in response, smiling and reaching out. As soon as her tiny hands touched the demon, it began screaming as smoke arose from its skin. Within seconds the hobgoblin had been disintegrated. "Ladies and gentlemen," Mephisto paused. "The ultimate weapon."

There was very loud chatter among the Vatican members. The Cardinal raised his hand and shushed them. "Very well. The girl is to be raised and trained at True Cross Academy as soon as she is of age. For now, we will take it upon one of our members to look after her. Are there any objections?" There was slight mumbling, but after what everyone witnessed, they all seemed to be happy to have her on their side. "Now girl," the Cardinal spoke in a much lighter tone. "Do you have a name?"

The little girl put her index finger on her chin as she let out a "Hmmmm.." With a smile she removed her hand from her chin and rested it on her hip. With confidence, she replied "The name is Mikako. I like Mika better though."

 **A/N: And so begins our journey! I'll try to get updates out as soon as possible. Like I said, I'm in the middle of moving so bear with me! See you guys soon!**


	3. Update

**A/N: I just wanted to pop in and express how sorry I am that I haven't updated in a while..** **My father recently passed away and I have been dealing with a lot and getting a lot of things settled. Now that everything is winding down, I have been able to find the time to sit down and actually write. Once again, I am deeply sorry, but the newest chapter will be posted by Monday.** **If not before. :D Much love guys.**


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